A system and process for recycling waste heat from foundry sand

Abstract

The present invention discloses a system and process for recycling waste heat of foundry sand, which relates to the technical field of lost foam casting, including a sand temperature regulating device, a steam boiler, a hot water tank, a paint room, a drying room and a constant pressure water replenishing device, wherein the sand temperature regulating device includes a primary heat exchanger, the bottom of the primary heat exchanger is connected to a secondary heat exchanger, the primary heat exchanger is respectively connected to the steam boiler, the hot water tank and the paint room through an insulation pipe, and the constant pressure water replenishing device is respectively connected to the water inlet ends of the primary heat exchanger and the secondary heat exchanger through a water pipe. The design of the present invention connects the sand temperature regulating device to the heating equipment of the workshop, heats the thermal medium by the waste heat of the hot sand, and transports the heated thermal medium to the heating equipment of the workshop, thereby reducing the natural gas consumed for heating the thermal medium, thereby reducing carbon emissions, reducing resource consumption while reducing production costs, and being beneficial to environmental protection.

Description

Technical Field

[0001] The invention relates to the technical field of lost foam casting, in particular to a system and process for recycling waste heat of foundry sand. Background Art

[0002] In the foundry industry, lost foam is one of the emerging and most advanced casting processes. The lost foam casting process usually involves first bonding a foam model that is similar in size and shape to the casting into a model, applying refractory coating and drying it, placing the model in a sand box, then filling it with dry sand and vibrating it, and finally pouring it under negative pressure to vaporize the model. The liquid metal occupies the position of the model, and forms a casting after solidification and cooling. After the casting is taken out of the sand mold, the entire sand mold disappears and becomes scattered sand again. Since the poured molten iron at about 1500℃ transfers heat to the sand, the sand must be cooled to below 60℃ for reuse. During the cooling period, the residual heat of the sand cannot be effectively utilized, which results in a large amount of heat waste.

[0003] In the production process of lost foam casting, some workshops require a lot of heat: the drying room for drying the outer coating of the lost foam, the paint line for spraying paint on the workpieces, and the steam boiler room. In the entire lost foam production process, the cost of heating the drying room and other workshops accounts for about 5% of the total process cost, and it will consume a lot of natural gas, which is not conducive to environmental protection. Summary of the invention

[0004] In order to overcome the above-mentioned defects existing in the prior art, the present invention provides a system and process for recovering waste heat of foundry sand.

[0005] The technical solution adopted by the present invention to solve its technical problems is: a foundry sand waste heat recovery and utilization system, including a sand temperature regulating device, a steam boiler, a hot water tank, a paint room, a drying room and a constant pressure water replenishing device, the sand temperature regulating device includes a primary heat exchanger, the bottom of the primary heat exchanger is connected to a secondary heat exchanger, the primary heat exchanger is connected to the steam boiler, the hot water tank and the paint room respectively through an insulation pipe, the hot water tank is used to store excess hot water in the system, a first temperature control valve is provided on the insulation pipe between the hot water tank and the primary heat exchanger, the secondary heat exchanger is connected to the hot water tank and the drying room respectively through an insulation pipe, a second temperature control valve is provided on the insulation pipe between the hot water tank and the secondary heat exchanger, the constant pressure water replenishing device is connected to the water inlet ends of the primary heat exchanger and the secondary heat exchanger respectively through a water pipe, and the constant pressure water replenishing device is used to add cold water to the pipeline to regulate the water temperature in the pipeline.

[0006] Furthermore, the water inlet end of the constant pressure water replenishment device is connected to a cold water tank, the cold water tank is connected to a softening water treatment device, the water outlet end of the constant pressure water replenishment device is respectively connected to the water inlet ends of the primary heat exchanger and the secondary heat exchanger, a first water replenishment valve is provided on the pipeline between the constant pressure water replenishment device and the primary heat exchanger, and a second water replenishment valve is provided on the pipeline between the constant pressure water replenishment device and the secondary heat exchanger.

[0007] Furthermore, the steam boiler is connected to the boiler feed water pump through an insulated water pipe, the boiler feed water pump is connected to the water outlet ends of the primary heat exchanger and the hot water tank through the insulated water pipe, a first solenoid valve is provided on the pipeline between the boiler feed water pump and the primary heat exchanger, a second solenoid valve is provided on the pipeline between the boiler feed water pump and the hot water tank, the boiler feed water pump is connected to the cold water tank through a water pipe, and a third solenoid valve is provided on the pipeline between the boiler feed water pump and the cold water tank.

[0008] Furthermore, the water inlet of the paint booth is connected to the water outlet of the primary heat exchanger through an insulated water pipe, a first pressure relief valve is provided at the water outlet of the primary heat exchanger, the water outlet of the paint booth is respectively connected to the water inlets of the hot water tank and the water reservoir, a liquid level control valve is provided on the pipeline between the water reservoir and the paint booth, a liquid level sensor is provided in the hot water tank, the water outlet of the hot water tank is connected to the hot water tank water pump through an insulated water pipe, a hot water tank valve is provided on the pipeline between the hot water tank and the hot water tank water pump, and the hot water tank water pump is connected to the water inlet of the primary heat exchanger.

[0009] Furthermore, the first temperature control valve is arranged at the water outlet end of the primary heat exchanger, and the first temperature control valve is connected to the water inlet end of the hot water tank through an insulated water pipe.

[0010] Furthermore, the second temperature control valve is arranged at the water outlet end of the secondary heat exchanger, and the second temperature control valve is connected to the water inlet end of the hot water tank through an insulated water pipe.

[0011] Furthermore, the water outlet end of the secondary heat exchanger is connected to the water inlet end of the drying room through an insulated water pipe, a second pressure relief valve is provided at the water outlet end of the secondary heat exchanger, the water outlet end of the drying room is connected to a drying room water pump through an insulated water pipe, a drying room valve is provided on the pipeline between the drying room water pump and the drying room, and the drying room water pump is connected to the water inlet end of the secondary heat exchanger.

[0012] Furthermore, a first elevator is provided on the side of the sand temperature regulating device, a sand bin is fixedly installed on the top of the first-level heat exchanger, and the sand bin is located below the discharge pipe of the first elevator, a drop hopper is fixedly installed on the bottom of the second-level heat exchanger, a conveying device is provided below the drop hopper, a second elevator is provided in front of the conveying device in the feeding direction, a secondary sand temperature regulating device is provided below the discharge pipe of the second elevator, the secondary sand temperature regulating device is connected to the third elevator through a material guide pipe, and a collecting box is provided below the discharge pipe of the third elevator.

[0013] Furthermore, the first-stage heat exchanger includes a heat exchange tube, and sealing plates are fixedly installed at the upper and lower ends of the heat exchange tube, and several groups of sand falling pipes are fixedly installed on the sealing plate. A water outlet and a water inlet are respectively opened on the side walls of the heat exchange tube. The structure of the second-stage heat exchanger is the same as that of the first-stage heat exchanger.

[0014] The beneficial effects of the present invention are:

[0015] 1. The design of the present invention is designed to connect the sand temperature regulating device with the heating equipment of the workshop. The waste heat of the hot sand is used to heat the thermal medium, and the heated thermal medium is transported to the heating equipment of the workshop, thereby reducing the natural gas consumed in heating the thermal medium, thereby reducing carbon emissions, reducing production costs while reducing resource consumption, and being beneficial to environmental protection.

[0016] 2. The design of the present invention is designed that temperature control valves are installed on the pipelines between the primary heat exchanger, the second heat exchanger and the hot water tank. The temperature control valve will automatically open when it detects that the temperature in the pipeline is higher than the set value, and the pressure in the pipeline is reduced by discharging the thermal medium into the hot water tank, so that the constant pressure water replenishment device can transport the low-temperature thermal medium into the pipeline, thereby automatically adjusting the temperature of the thermal medium in the pipeline, ensuring the heat exchange effect while avoiding excessive heating temperature.

[0017] A foundry sand waste heat recovery process comprises the following steps:

[0018] S1. Recycling of waste heat from high-temperature hot sand. The hot sand generated by lost foam casting is transported to the sand bin through the first elevator. The hot sand enters the primary heat exchanger through the sand bin and reacts with the thermal medium in the primary heat exchanger.

[0019] S2. Low-temperature hot sand waste heat recovery: the hot sand in the primary heat exchanger enters the secondary heat exchanger, exchanges heat with the thermal medium in the secondary heat exchanger, and transfers heat to the thermal medium;

[0020] S3. Hot sand recovery: the hot sand in the secondary heat exchanger falls onto the conveying device, which conveys the hot sand to the second elevator. The second elevator conveys the hot sand to the secondary sand temperature regulating device, where the hot sand is cooled to the recovery temperature through the thermal medium. The hot sand is conveyed to the third elevator through the guide pipe, and the third elevator conveys the cooled molding sand to the collection box for storage.

[0021] The production process of the present invention uses a multi-stage cooling method to make the hot sand undergo multi-stage heat exchange treatment, thereby achieving multi-stage heating to meet the heating needs of different production workshops, thereby maximizing the use of resources and avoiding waste of resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0023] Figure 1 This is a schematic diagram of the waste heat recovery system of the present invention;

[0024] Figure 2 It is a structural schematic diagram of the waste heat recovery equipment of the present invention;

[0025] Figure 3 It is a structural schematic diagram of the primary heat exchanger of the present invention.

[0026] In the figure: 1. Steam boiler, 2. Boiler water supply pump, 3. First solenoid valve, 4. Second solenoid valve, 5. Third solenoid valve, 6. Hot water tank, 7. Hot water tank pump, 8. Hot water tank valve, 9. First pressure safety valve, 10. Paint room, 11. Drying room, 12. Drying room pump, 13. Drying room valve, 14. Constant pressure water supply device, 15. Cold water tank, 16. Softened water treatment device, 17. First water supply valve, 18. Second water supply valve, 19. Reservoir, 20. Liquid level control valve, 21. First temperature control valve , 22. Second temperature control valve, 23. Second pressure safety valve, 100. Sand temperature regulating device, 101. Primary heat exchanger, 102. Heat exchange cylinder, 103. Sealing plate, 104. Sand falling pipe, 105. Water outlet, 106. Water inlet, 107. Secondary heat exchanger, 108. Drop hopper, 109. Conveying device, 110. First elevator, 111. Second elevator, 112. Secondary sand temperature regulating device, 113. Material guide pipe, 114. Third elevator, 115. Collecting box, 116. Sand bin. DETAILED DESCRIPTION

[0027] In order to more clearly illustrate the technical solution of the present invention, the present invention is further described below in conjunction with the accompanying drawings. Obviously, the accompanying drawings described below are only one embodiment of the present invention. For ordinary technicians in this field, without paying any creative work, other embodiments can be obtained based on this drawing and embodiment, which all belong to the protection scope of the present invention.

[0028] according to Figure 1 As shown, a system for recycling waste heat from foundry sand comprises a sand temperature regulating device 100, a steam boiler 1, a hot water tank 6, a paint room 10, a drying room 11 and a constant pressure water supply device 14. The sand temperature regulating device 100 comprises a primary heat exchanger 101. The bottom of the primary heat exchanger 101 is connected to a secondary heat exchanger 107. The primary heat exchanger 101 is connected to the steam boiler 1, the hot water tank 6 and the paint room 10 through insulation pipes. The hot water tank 6 is used to store excess hot water in the system. A first temperature control valve 21 is provided on the insulation pipeline between the hot water tank 6 and the primary heat exchanger 101, and the secondary heat exchanger 107 is respectively connected to the hot water tank 6 and the drying room 11 through insulation pipes. A second temperature control valve 22 is provided on the insulation pipeline between the hot water tank 6 and the secondary heat exchanger 107, and the constant pressure water replenishment device 14 is respectively connected to the water inlet ends of the primary heat exchanger 101 and the secondary heat exchanger 107 through water pipes. The constant pressure water replenishment device 14 is used to add cold water to the pipeline to adjust the water temperature in the pipeline.

[0029] In the above specific embodiment, the hot sand passes through the primary heat exchanger 101 and the secondary heat exchanger 107 in sequence, and the hot sand transfers heat to the water in the heat exchanger, and heats the water in the heat exchanger by the hot sand. Since the hot sand first passes through the primary heat exchanger 101, the water temperature in the primary heat exchanger 101 is higher than the water temperature in the secondary heat exchanger 107. The high-temperature water in the primary heat exchanger 101 supplies the steam boiler 1 and the paint room 10 with higher heat demand, and the low-temperature water in the secondary heat exchanger 107 supplies the drying room 11. After the water temperature in the pipeline is higher than the set temperature, the first temperature control valve 21 and the second temperature control valve 22 are opened to discharge the hot water into the hot water tank 6 for storage. While the hot water is discharged into the hot water tank 6, cold water is added to the pipeline through the constant pressure water replenishment device 14 to adjust the water temperature in the pipeline, thereby reducing the cost required for heating the workshop, and then reducing the consumption of resources such as natural gas, which is beneficial to environmental protection.

[0030] The present embodiment provides a foundry sand waste heat recovery system. The softening water treatment device 16 is connected to the water supply pipe to soften the water entering the system to avoid scale generation in the pipes and heating equipment in the system. The softened water enters the cold water tank 15 for storage. The opening water temperature of the first water supply valve 17 and the second water supply valve 18 can be set. The preferred opening water temperature of the first water supply valve 17 is 120°C and the closing water temperature is 115°C. The preferred opening water temperature of the second water supply valve 18 is 95°C and the closing water temperature is 92°C. When the water temperature in the pipeline is higher than the set value, the corresponding water supply valve will open to replenish cold water into the pipeline. The specific technical scheme is as follows:

[0031] The water inlet end of the constant pressure water replenishment device 14 is connected to a cold water tank 15, and the cold water tank 15 is connected to a softening water treatment device 16. The water outlet end of the constant pressure water replenishment device 14 is respectively connected to the water inlet ends of the primary heat exchanger 101 and the secondary heat exchanger 107. A first water replenishment valve 17 is provided on the pipeline between the constant pressure water replenishment device 14 and the primary heat exchanger 101, and a second water replenishment valve 18 is provided on the pipeline between the constant pressure water replenishment device 14 and the secondary heat exchanger 107.

[0032] The present embodiment provides a system for recycling waste heat from foundry sand. When the lost foam casting production line is working, the first solenoid valve 3 is opened, the second solenoid valve 4 and the third solenoid valve 5 are closed, and the hot water in the primary heat exchanger 101 is supplied to the steam boiler 1. When the steam boiler 1 is short of water, the boiler water supply pump 2 is started to transport the hot water in the primary heat exchanger 101 to the steam boiler 1. The steam produced by the steam boiler 1 is supplied to the lost foam manufacturing workshop. When the lost foam casting production line is stopped and there is sufficient water in the hot water tank 6, the second solenoid valve 4 is opened, the first solenoid valve 3 and the third solenoid valve 5 are closed, and the hot water in the hot water tank 6 is supplied to the steam boiler 1. When there is a shortage of water in the hot water tank 6, the third solenoid valve 5 is opened, the first solenoid valve 3 and the second solenoid valve 4 are closed, and the water in the cold water tank 15 is supplied to the steam boiler 1. The specific technical scheme is as follows:

[0033] The steam boiler 1 is connected to the boiler feed water pump 2 through an insulated water pipe, and the boiler feed water pump 2 is connected to the water outlet ends of the primary heat exchanger 101 and the hot water tank 6 through the insulated water pipe. A first solenoid valve 3 is provided on the pipeline between the boiler feed water pump 2 and the primary heat exchanger 101, and a second solenoid valve 4 is provided on the pipeline between the boiler feed water pump 2 and the hot water tank 6. The boiler feed water pump 2 is connected to the cold water tank 15 through a water pipe, and a third solenoid valve 5 is provided on the pipeline between the boiler feed water pump 2 and the cold water tank 15.

[0034] The present embodiment provides a system for recycling waste heat of foundry sand. When the lost foam casting production line is working, the hot water tank valve 8 is opened, and the hot water is circulated in the primary heat exchanger 101, the paint room 10 and the hot water tank 6 through the hot water tank water pump 7, so as to heat the paint room 10. The heating temperature of the paint room 10 is controlled by setting the opening and closing water temperatures of the first temperature control valve 21. The opening and closing water temperatures of the first temperature control valve 21 should be the same as the setting value of the first water supply valve 13. When the water temperature in the pipeline is higher than the setting value, the first temperature control valve 21 is opened to discharge part of the hot water into the hot water tank 6, thereby releasing the pressure in the pipeline, and then allowing cold water to enter the pipeline. When the water temperature in the pipeline is lower than the setting value, the first temperature control valve 21 is closed, while ensuring the heat exchange effect of the primary heat exchanger 101, the temperature in the paint room 10 is prevented from being too high. When the water in the hot water tank 6 is full, the liquid level control valve 20 is opened to allow the hot water to enter the water reservoir 19 for storage. The specific technical scheme is as follows:

[0035] The water inlet of the paint booth 10 is connected to the water outlet of the primary heat exchanger 101 through an insulated water pipe. A first pressure safety valve 9 is provided at the water outlet of the primary heat exchanger 101. The setting value of the first pressure safety valve 9 is 0.3MPa-0.4MPa. When the pipeline pressure is higher than the setting value, the first pressure safety valve 9 opens to release the pressure. The water outlet of the paint booth 10 is respectively connected to the water inlets of the hot water tank 6 and the water reservoir 19. A liquid level control valve 20 is provided on the pipeline between the water reservoir 19 and the paint booth 10. A liquid level sensor is provided in the hot water tank. The water outlet of the hot water tank 6 is connected to a hot water tank pump 7 through an insulated water pipe. A hot water tank valve 8 is provided on the pipeline between the hot water tank 6 and the hot water tank pump 7. The hot water tank pump 7 is connected to the water inlet of the primary heat exchanger 101.

[0036] The first temperature control valve 21 is arranged at the water outlet of the primary heat exchanger 101 , and the first temperature control valve 21 is connected to the water inlet of the hot water tank 6 through an insulated water pipe.

[0037] The present embodiment provides a system for recycling waste heat from foundry sand. After the hot sand undergoes a heat exchange in the primary heat exchanger 101, the temperature of the hot sand itself is greatly reduced. The temperature of the hot water in the secondary heat exchanger 107 cannot meet the heating demand of the steam boiler 1 and the paint room 10. Therefore, the hot water in the secondary heat exchanger 107 is supplied to the drying room 11 with a lower heating demand. The hot water is circulated between the secondary heat exchanger 107 and the drying room 11 through the drying room water pump 12. The heating temperature of the drying room 11 is controlled by setting the opening and closing water temperatures of the second temperature control valve 22. The opening and closing water temperatures of the second temperature control valve 22 should be the same as the set value of the second water supply valve 18. When the water temperature in the pipeline is higher than the set value, the second temperature control valve 22 is opened to discharge part of the hot water into the hot water tank 6, thereby releasing the pressure in the pipeline and allowing cold water to enter the pipeline. When the water temperature in the pipeline is lower than the set value, the second temperature control valve 22 is closed. The specific technical solution is as follows:

[0038] The second temperature control valve 22 is arranged at the water outlet of the secondary heat exchanger 107 , and the second temperature control valve 22 is connected to the water inlet of the hot water tank 6 through an insulated water pipe.

[0039] The water outlet end of the secondary heat exchanger 107 is connected to the water inlet end of the drying room 11 through an insulated water pipe. A second pressure safety valve 23 is provided at the water outlet end of the secondary heat exchanger 107. The setting value of the second pressure safety valve 23 is also 0.3MPa-0.4MPa. The water outlet end of the drying room 11 is connected to the drying room water pump 12 through an insulated water pipe. A drying room valve 13 is provided on the pipeline between the drying room water pump 12 and the drying room 11. The drying room water pump 12 is connected to the water inlet end of the secondary heat exchanger 107.

[0040] The present embodiment provides a system for recycling waste heat of foundry sand. The foundry sand is transported to a sand bin 116 at the top of a primary heat exchanger 101 through a first elevator 110. The sand bin 116 is connected to a sand falling pipe 104 inside the primary heat exchanger 101. The sand falling pipe 104 in the primary heat exchanger 101 and the sand falling pipe 104 in the secondary heat exchanger 107 are connected end to end. The foundry sand passes through the primary heat exchanger 101 and the secondary heat exchanger 107 in sequence along the sand falling pipe 104. The thermal medium circulates in and out of the heat exchanger through a water outlet 105 and a water inlet 106. The water outlet 105 is arranged above the water inlet 106 to facilitate the circulation of hot water in the heat exchanger. The heat of the foundry sand is transferred to the thermal medium through the tube wall of the sand falling pipe 104. The foundry sand passes through the secondary heat exchanger 107. After the first heat exchanger 107, it falls into the drop hopper 108, and then falls from the drop hopper 108 to the conveying device 109. The conveying device 109 preferably adopts a belt conveyor. The conveying device 109 conveys the molding sand to the second elevator 111, and then conveys it to the second sand temperature regulating device 112 through the second elevator. The second sand temperature regulating device is provided with a sand bin 116 and a group of heat exchangers. The guide pipe 113 is installed at the bottom of the heat exchanger. The feed end of the guide pipe 113 is provided with a valve. When the molding sand is cooled to below 60°C, the valve of the guide pipe 113 is opened to guide the molding sand into the third elevator 114. Finally, the molding sand is transported to the collection box 115 for storage through the third elevator 114, so as to facilitate the recycling of the molding sand. The specific technical scheme is as follows:

[0041] like Figure 2 and Figure 3 As shown, a first elevator 110 is provided on the side of the sand temperature regulating device 100, a sand bin 116 is fixedly installed on the top of the first heat exchanger 101, and the sand bin 116 is located below the discharge pipe of the first elevator 110, and a drop hopper 108 is fixedly installed on the bottom of the second heat exchanger 107, and a conveying device 109 is provided below the drop hopper 108, and a second elevator 111 is provided in front of the conveying device 109 in the feeding direction, and a secondary sand temperature regulating device 112 is provided below the discharge pipe of the second elevator 111, and the secondary sand temperature regulating device 112 is connected to the third elevator 114 through a guide pipe 113, and a collecting box 115 is provided below the discharge pipe of the third elevator 114.

[0042] The primary heat exchanger 101 includes a heat exchange tube 102, and sealing plates 103 are fixedly installed at the upper and lower ends of the heat exchange tube 102. A plurality of groups of sand falling pipes 104 are fixedly installed on the sealing plate 103. A water outlet 105 and a water inlet 106 are respectively opened on the side walls of the heat exchange tube 102. The structure of the secondary heat exchanger 107 is the same as that of the primary heat exchanger 101.

[0043] A foundry sand waste heat recovery process comprises the following steps:

[0044] S1. The high-temperature hot sand generated by lost foam casting is transported to the sand bin 116 through the first elevator 110. At this time, the temperature of the hot sand is about 100°C-300°C. The hot sand enters the primary heat exchanger 101 through the sand bin 116 and performs heat exchange with the thermal medium in the primary heat exchanger 101. After the heat exchange between the thermal medium and the hot sand, the temperature reaches about 90°C-130°C.

[0045] S11. When the lost foam casting production line is working, the first solenoid valve 3 is opened, the second solenoid valve 4 and the third solenoid valve 5 are closed, the boiler feed pump 2 is started, and the thermal medium in the primary heat exchanger 101 is preferentially supplied to the steam boiler 1;

[0046] S12. After the steam boiler 1 is full of water, the boiler water supply pump 2 stops working. When the water temperature is higher than 120°C, the first temperature control valve 21 opens, and part of the thermal medium is directly transported to the hot water tank 10 through the hot water tank pump 7. At the same time, the first water supply valve 17 opens, and the low-temperature thermal medium in the cold water tank 15 is transported to the pipeline through the constant pressure water supply device 14. When the water temperature drops below 115°C, the first temperature control valve 21 is closed, and the first water supply valve 17 is also closed synchronously, so that the thermal medium circulates between the paint room 10, the hot water tank 6 and the primary heat exchanger 101;

[0047] S13 When the hot water tank 6 is at a high water level, the liquid level control valve 20 opens, and the thermal medium in the paint room 10 flows into the water reservoir 19;

[0048] S2. The hot sand in the primary heat exchanger 101 enters the secondary heat exchanger 107. At this time, the temperature of the hot sand is reduced to about 80°C-200°C, and heat is exchanged with the thermal medium in the secondary heat exchanger 107. After the heat exchange between the thermal medium and the hot sand, the temperature reaches about 90°C.

[0049] S21. The drying room water pump 12 supplies the thermal medium in the secondary heat exchanger to the drying room 11. When the water temperature is higher than 95°C, the second temperature control valve 22 opens, and the thermal medium enters the hot water tank 6. At this time, the pressure in the pipeline decreases, and the second water supply valve 18 opens to transport the low-temperature thermal medium in the cold water tank 15 to the pipeline; when the water temperature is lower than 90°C, the second temperature control valve 22 is closed, and the second water supply valve 18 is also closed synchronously, so that the thermal medium circulates between the drying room 11 and the secondary heat exchanger 107;

[0050] S3. The hot sand in the secondary heat exchanger 107 falls onto the conveying device 109, and the conveying device 109 conveys the hot sand to the second elevator 111. The hot sand is then conveyed to the secondary sand temperature regulating device 112 through the second elevator 111. At this time, the temperature of the hot sand is about 70°C-100°C. After the hot sand is cooled to below 60°C by the thermal medium, the hot sand is conveyed to the third elevator 114 through the guide pipe 113. The third elevator 114 then conveys the cooled molding sand to the collection box 115 for storage.

[0051] The above embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention. The protection scope of the present invention is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present invention within the essence and protection scope of the present invention, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present invention.

Claims

1. A foundry sand waste heat recovery system, characterized in that: The invention comprises a sand temperature regulating device (100), a steam boiler (1), a hot water tank (6), a paint room (10), a drying room (11) and a constant pressure water supply device (14), wherein the sand temperature regulating device (100) comprises a primary heat exchanger (101), the bottom of which is connected to a secondary heat exchanger (107), the primary heat exchanger (101) is connected to the steam boiler (1), the hot water tank (6) and the paint room (10) through insulation pipes, the hot water tank (6) is used to store excess hot water in the system, and the hot water tank (6) is connected to the primary heat exchanger (107). 1), a first temperature control valve (21) is provided on the insulation pipeline between the paint room (10), the water inlet end of the paint room (10) is connected to the water outlet end of the primary heat exchanger (101) through an insulation water pipe, a first pressure safety valve (9) is provided at the water outlet end of the primary heat exchanger (101), the water outlet end of the paint room (10) is connected to the water inlet ends of the hot water tank (6) and the water reservoir (19) respectively, a liquid level control valve (20) is provided on the pipeline between the water reservoir (19) and the paint room (10), a liquid level sensor is provided in the hot water tank, and the water outlet end of the hot water tank (6) is connected to the hot water tank (6) through an insulation water pipe. A hot water tank pump (7) is provided on the pipeline between the hot water tank (6) and the hot water tank pump (7), the hot water tank valve (8) is provided on the pipeline between the hot water tank (6) and the hot water tank pump (7), the hot water tank pump (7) is connected to the water inlet end of the primary heat exchanger (101), the secondary heat exchanger (107) is connected to the hot water tank (6) and the drying room (11) respectively through the insulation pipeline, a second temperature control valve (22) is provided on the insulation pipeline between the hot water tank (6) and the secondary heat exchanger (107), the water outlet end of the secondary heat exchanger (107) is connected to the water inlet end of the drying room (11) through the insulation water pipe, and the secondary heat exchanger (107) ) is provided at the water outlet of the drying room (11); the water outlet of the drying room (11) is connected to a drying room water pump (12) via an insulated water pipe; a drying room valve (13) is provided on the pipeline between the drying room water pump (12) and the drying room (11); the drying room water pump (12) is connected to the water inlet of the secondary heat exchanger (107); the constant pressure water replenishing device (14) is connected to the water inlet of the primary heat exchanger (101) and the secondary heat exchanger (107) via a water pipe; the constant pressure water replenishing device (14) is used to replenish cold water into the pipeline to adjust the water temperature in the pipeline.

2. A foundry sand waste heat recovery system according to claim 1, characterized in that: The water inlet end of the constant pressure water replenishment device (14) is connected to a cold water tank (15), and the cold water tank (15) is connected to a softening water treatment device (16). The water outlet end of the constant pressure water replenishment device (14) is respectively connected to the water inlet ends of a primary heat exchanger (101) and a secondary heat exchanger (107). A first water replenishment valve (17) is provided on the pipeline between the constant pressure water replenishment device (14) and the primary heat exchanger (101), and a second water replenishment valve (18) is provided on the pipeline between the constant pressure water replenishment device (14) and the secondary heat exchanger (107).

3. A foundry sand waste heat recovery system according to claim 2, characterized in that: The steam boiler (1) is connected to a boiler feed water pump (2) via an insulated water pipe, the boiler feed water pump (2) is connected to a primary heat exchanger (101) and a water outlet of a hot water tank (6) via the insulated water pipe, a first solenoid valve (3) is provided on the pipeline between the boiler feed water pump (2) and the primary heat exchanger (101), a second solenoid valve (4) is provided on the pipeline between the boiler feed water pump (2) and the hot water tank (6), the boiler feed water pump (2) is connected to a cold water tank (15) via a water pipe, and a third solenoid valve (5) is provided on the pipeline between the boiler feed water pump (2) and the cold water tank (15).

4. The foundry sand waste heat recovery system according to claim 1, characterized in that: The first temperature control valve (21) is arranged at the water outlet of the primary heat exchanger (101), and the first temperature control valve (21) is connected to the water inlet of the hot water tank (6) via an insulated water pipe.

5. The foundry sand waste heat recovery system according to claim 1, characterized in that: The second temperature control valve (22) is arranged at the water outlet end of the secondary heat exchanger (107), and the second temperature control valve (22) is connected to the water inlet end of the hot water tank (6) through an insulated water pipe.

6. The foundry sand waste heat recovery system according to claim 1, characterized in that: A first elevator (110) is provided on the side of the sand temperature regulating device (100); a sand bin (116) is fixedly installed on the top of the first heat exchanger (101); the sand bin (116) is located below the discharge pipe of the first elevator (110); a drop hopper (108) is fixedly installed on the bottom of the second heat exchanger (107); a conveying device (109) is provided below the drop hopper (108); a second elevator (111) is provided in front of the conveying device (109) in the feeding direction; a second sand temperature regulating device (112) is provided below the discharge pipe of the second elevator (111); the second sand temperature regulating device (112) is connected to a third elevator (114) through a material guide pipe (113); and a collecting box (115) is provided below the discharge pipe of the third elevator (114).

7. A foundry sand waste heat recovery system according to claim 6, characterized in that: The primary heat exchanger (101) comprises a heat exchange tube (102), the upper and lower ends of the heat exchange tube (102) are fixedly mounted with sealing plates (103), a plurality of groups of sand falling pipes (104) are fixedly mounted on the sealing plates (103), a water outlet (105) and a water inlet (106) are respectively provided on the side walls of the heat exchange tube (102), and the structure of the secondary heat exchanger (107) is the same as that of the primary heat exchanger (101).

8. A foundry sand waste heat recovery process, characterized in that: The process is used in a foundry sand waste heat recovery system as described in any one of claims 1 to 7, and comprises the following steps: S1. Recycling the waste heat of high-temperature hot sand. The hot sand generated by lost foam casting is transported to the sand bin (116) through the first elevator (110). The hot sand enters the primary heat exchanger (101) through the sand bin (116) and exchanges heat with the thermal medium in the primary heat exchanger (101), transferring heat to the thermal medium. S2. Low-temperature hot sand waste heat recovery, the hot sand in the primary heat exchanger (101) enters the secondary heat exchanger (107), exchanges heat with the thermal medium in the secondary heat exchanger (107), and transfers heat to the thermal medium; S3. Hot sand recovery: the hot sand in the secondary heat exchanger (107) falls onto the conveying device (109), the conveying device (109) conveys the hot sand to the second elevator (111), the second elevator (111) conveys the hot sand to the secondary sand temperature regulating device (112), the hot sand is cooled to the recovery temperature by the thermal medium, the hot sand is conveyed to the third elevator (114) through the material guide pipe (113), and the third elevator (114) conveys the cooled molding sand to the collection box (115) for storage.

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